Semiconductor devices such as a plurality of semiconductor integrated circuits formed on each chip region of a semiconductor wafer are subjected to an electrical test for determining whether or not each one is produced as per specification. In an electrical test of this type, a probe assembly generally called a probe card is used. When a plurality of probes (contacts) provided on a probe base plate of this probe assembly are pressed against the corresponding electrodes of a device under test, the device under test is connected to a tester for electrical test through the probe assembly.
Among probes of a probe assembly of this type, there is a blade-type one formed by using a photolithography technique (Japanese Patent Appln. Public Disclosure No. 2004-340654). This blade-type probe includes a plate-like blade body. The plate-like blade body has a mounting portion on a support base plate, a rising portion which rises from the mounting portion, and an arm portion extending laterally from the rising portion on a plane which includes this rising portion. At the front end of the arm portion of the blade body, a tip projecting from the side opposing the side where the mounting portion is located is formed. In order to surely press the tip against an electrode of a device under test, the blade body is generally made of a highly tenacious (flexible) metal material such as nickel and its alloy. However, because of comparatively high electrical resistance, such a metal material has a problem in accurate repeatability of a rectangular wave signal used for an electrical test.
Thus, the Applicant of this Application proposed earlier, as shown in FIG. 8 in Japanese Patent Application 2005-163546 or International Patent Application PCT/JP2005/014871, to cover the surface of the body 2 of a probe 1 with a rolled gold layer 3 to make this rolled gold layer 3 function as an electrically conducting path, thereby to lower the electrical resistance of the probe.
Compared with a metal material which forms the probe body 2, the rolled gold layer 3 is superior in wettability relative to a solder 4 such as tin or tin alloy, and this rolled gold layer 3 covers the surface of the probe body 2. Thus, when the solder 4 is used to combine the probes 1 with a wiring path 5 provided on the support base plate of the probe assembly, the wettability of the rolled gold layer 3 sometimes causes the solder 4 to spread farther than required in a direction (upward in FIG. 8) to be away from a base end combining the probe body 2 with the wiring path 5.
Such an excessive spread of the solder 4 due to the wettability of the rolled gold layer 3 complicates formation of an adequate fillet shape for the solder 4 to display a stable bond strength and becomes a bar to the stable bond strength between the probes and the support base plate where the probes are to be soldered.